JP3740922B2 - Vibration isolator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inner cylinder fitting, an outer cylinder fitting arranged on the outer side in the radial direction, and a rubber elastic body that is interposed between the inner cylinder fitting and the outer cylinder fitting and elastically connects between the two fittings. And a vibration isolator that is supported by a support shaft member that is press-fitted into the shaft hole of the inner cylinder fitting.
[0002]
[Prior art]
Conventionally, as this type of vibration isolator, for example, a differential mount for a vehicle as shown in FIG. 5 is known. This vibration isolator is formed by vulcanization molding between the inner cylinder fitting 1, the outer cylinder fitting 2 disposed on the radially outer side of the inner cylinder fitting 1, and the inner cylinder fitting 1 and the outer cylinder fitting 2. And a rubber elastic body 3 that elastically connects both metal fittings. The rubber elastic body 3 is provided with a so-called curly portion 4 which is an annular cavity extending from the both ends in the axial direction along the vicinity of the inner wall of the outer tube fitting 2 in the axial direction and extending over the entire circumference in the circumferential direction. By providing such a curled portion 4, it is possible to adjust so as to soften the radial spring characteristics of the vibration isolator.
[0003]
A support shaft member 6 for cantilever support is fixed by being press-fitted into the shaft hole 1a of the inner cylindrical metal fitting 1. The press-fitting allowance (degree of diameter expansion) of the inner cylindrical metal fitting 1 by the press-fitting of the support shaft member 6 is about 0.1 to 0.5 mm, whereby the support shaft member 6 is firmly fixed to the inner cylindrical metal fitting 1. Thus, the pulling force is set to the same level as the pressure input. Then, the outer cylinder fitting 3 is press-fitted and fixed to a support bracket of a differential gear case (not shown), the bolt portion of the support shaft member 6 is inserted into a mounting hole of a body subframe (not shown), and a nut is screwed to the tip portion thereof. By attaching it, the vibration isolator is cantilevered by the body subframe.
[0004]
By the way, in the above vibration isolator, in order to suppress the amplitude to an appropriate width with respect to excessive vibration input, as shown as a comparative example in FIG. An annular stopper portion 5 is attached. The stopper portion 5 can be made of resin or metal, and is preferably made of resin from the viewpoint of reducing the weight of the vibration isolator.
[0005]
[Problems to be solved by the invention]
However, since the support shaft member is pressed into the shaft hole of the inner cylinder fitting after the stopper portion is fixed to the inner cylinder fitting, a large pressing force is applied to the stopper portion due to the expansion of the inner cylinder fitting. . Therefore, when a resin stopper is used, the resin is fragile to tensile stress. There is a problem that it becomes insufficient and its durability is impaired.
[0006]
In addition, when using a metal stopper part formed by forging or the like integrally with the inner cylinder metal fitting or a stopper part formed by forging or the like and press-fitted into the inner cylinder metal fitting, the support shaft member is press-fitted into the inner cylinder metal fitting. By doing so, the portion of the inner cylinder fitting without the stopper portion is elastically deformed, and the portion provided with the stopper portion is plastically deformed because the resistance during press-fitting is increased. As a result of such plastic deformation, the pulling force of the support shaft member is reduced to about half of the pressure input, and as a result, the function of stably supporting the inner cylindrical fitting of the support shaft member is impaired. It will be.
[0007]
The present invention is intended to solve the above-described problem, and the stopper portion is not damaged by press-fitting the support shaft member into the shaft hole of the inner cylindrical metal fitting in which the stopper portion is fixed to the outer peripheral surfaces on both axial ends. And it aims at providing the anti-vibration apparatus with which the appropriate extraction force of a support shaft member is ensured.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the structural feature of the invention of claim 1 is that both end portions in the axial direction of the metal pipe bulge coaxially with respect to the intermediate portion therebetween, An inner cylindrical fitting whose inner diameter and outer diameter are larger than the inner diameter and outer diameter of the intermediate portion, a pair of stopper portions that are fixed to the outer peripheral surface of each large diameter portion and project in the radial direction, An outer cylinder fitting disposed radially outside the inner cylinder fitting including a pair of stopper portions, and interposed between the inner cylinder fitting and the outer cylinder fitting, elastically between the inner cylinder fitting and the outer cylinder fitting. The support shaft member is provided with a rubber elastic body to be connected, and is press-fitted and fixed in the shaft hole of the inner cylinder fitting, so that only the middle portion of the inner cylinder fitting is elastically expanded, and the large diameter portion of the inner cylinder fitting Is to be supported so as not to be affected by press-fitting .
[0009]
In the invention of claim 1 configured as described above, both end portions in the axial direction including an arrangement portion of the stopper portion in the inner cylindrical metal fitting have an inner diameter and an outer diameter that are other than the inner diameter and the outer diameter. The larger diameter part is slightly larger. Therefore, when the support shaft member is press-fitted into the shaft hole of the inner cylinder fitting to support the vibration isolator, the intermediate portion excluding the large diameter portion of the inner cylinder fitting is slightly elastically expanded. Then, it is not directly influenced by the press-fitting of the support shaft member. As a result, when the stopper portion is made of resin, the strength does not decrease even when the support shaft member is press-fitted. In addition, when the stopper portion is made of metal, by pressing the support shaft member into the inner cylinder fitting, only the small diameter intermediate portion other than the large diameter portion of the inner cylinder fitting is elastically deformed. There is no plastic deformation.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIGS. 1 and 2 show a vibration isolator for a vehicle differential mount according to the embodiment, an axial sectional view and an axial perpendicular sectional view. It is shown by.
[0011]
The vibration isolator is provided with an inner cylindrical metal fitting 11 which is a pipe-like straight metal fitting, and the inner cylindrical metal fitting 11 has an approximately 1/3 length portion in the middle in the axial direction from both ends in the axial direction. The pair of large-diameter portions 12 and 12 slightly bulge coaxially in the radial direction with respect to the portion 3. That is, the inner diameter and the outer diameter of the large diameter portions 12 and 12 are slightly larger than the inner diameter and the outer diameter of the intermediate portion 13 sandwiched between the large diameter portions 12 and 12. The boundaries between the large-diameter portions 12 and 12 and the intermediate portion 13 are inclined portions 14 and 14 that connect both sides having different diameters with a small portion in the axial direction. The large-diameter portions 12 and 12 are formed, for example, by holding the intermediate portion 13 of the pipe-shaped metal fitting that is not expanded in diameter with its outer peripheral surface covered by a fixing jig (not shown), and only the both end portions to be expanded in diameter. With the bulge processing method (expansion processing method) etc. in which high pressure liquid is injected into the pipe and only the end portions are coaxially expanded radially outward by the fluid pressure Done. Between the intermediate position in the axial direction of each large-diameter portion 12, 12 and the position in the vicinity of the intermediate portion 13, annular stopper portions 15, 15 projecting in the radial direction along the entire circumference of the outer peripheral surface are fixed.
[0012]
The stopper portions 15 and 15 are made of resin, and are preferably made of a material whose hardness is increased by adding about 15% to 45% of glass fiber to a polyamide-based resin such as nylon 6-6. The stopper portions 15 and 15 are usually formed integrally with the outer peripheral surface of the inner cylindrical metal member 11 by injection molding using these resin materials. Therefore, the stopper portions 15 and 15 are formed with high productivity and inexpensively provided. In addition, the outer peripheral surface of the stopper portions 15 and 15 disposed portions of the inner cylindrical metal fitting 11 is subjected to knurling or the like in advance to roughen the surface, so that the adhesion of the resin is enhanced. However, the attachment of the stoppers 15, 15 to the inner cylinder fitting 11 is not limited to this, and a pre-formed annular stopper is fitted on the outer peripheral surface of the large diameter part 12 of the inner cylinder fitting 11 and bonded. It may be fixed.
[0013]
On the outer peripheral side of the inner cylinder fitting 11 including the stopper portions 15 and 15, an outer cylinder fitting 16 which is a thin cylindrical pipe is coaxially disposed. Between the outer cylinder fitting 16 and the inner cylinder fitting 11, a rubber elastic body 18 is integrally formed over the entire circumference by vulcanization molding, and the two fittings 11 and 16 are elastically connected. As shown in FIGS. 1 and 2, the rubber elastic body 18 extends from the both ends in the axial direction to the substantially both end positions of the intermediate portion 13 between the inner wall surface of the outer tube fitting 16 and the outer peripheries of the stopper portions 15 and 15. A pair of curly portions 19 and 19 which are annular space portions extending in the whole direction are provided.
[0014]
In the vibration isolator thus formed, as shown in FIG. 3, the insertion portion 22 of the support shaft member 21 is press-fitted over almost the entire length in the shaft hole 11 a of the inner tube fitting 11, thereby The intermediate portion 13 of the metal fitting 11 is expanded in the radial direction, and the insertion portion 22 is firmly inserted and fixed to the inner tube metal fitting 11. Here, both end sides including the arrangement portions of the stopper portions 15 and 15 of the inner cylindrical metal fitting 11 are formed in the large diameter portions 12 and 12 having an inner and outer diameter slightly larger than the inner and outer diameters of the intermediate portion 13 therebetween. When the support shaft member 21 is press-fitted into the shaft hole 11a of the inner cylindrical metal fitting 11, only the intermediate portion 13 is expanded in diameter by elastic deformation due to the press-fitting, and the inner periphery of the large diameter portions 12 and 12 and the support shaft member 21 A slight gap is interposed between the outer periphery of the insertion portion 22. Therefore, the large-diameter portion 12 is not affected at all by being expanded by the press-fitting of the support shaft member 21. That is, since the resin stopper portions 15 and 15 do not receive a radially outward force, the strength does not decrease, and the reliability is ensured over a long period of time. Further, since the support shaft member 21 receives the elastic reaction force from the intermediate portion 13 of the inner cylindrical metal member 11, the pulling force is appropriately ensured equivalent to the pressure input without decreasing.
[0015]
The vibration isolator into which the support shaft member 21 is press-fitted is fixed by press-fitting the outer cylinder fitting 16 into an insertion hole of a differential gear box (not shown). On the other hand, the support shaft member 21 is fixed to the vehicle body side subframe by inserting the support portion 24 of the support shaft member 21 into the vehicle body side subframe and screwing a nut to a bolt portion (not shown). Cantilevered.
[0016]
When the vibration input in the vertical direction of the vehicle is applied to the inner cylinder fitting 11, the vibration isolator attenuates the vibration input by the vibration absorbing action of the rubber elastic body 18 and suppresses the propagation of vibration to the differential gear box. Can do. Further, when the vibration input in the vertical direction increases, the stopper portions 15 and 15 come into contact with the inner wall surface of the outer tube fitting 28, thereby suppressing the vibration amplitude and enhancing the vibration damping effect of the vibration isolator. That is, with this vibration isolator, vibration can be damped both when normal vibration (such as a booming sound) is input and when large vibration (such as a drone sound) is input. Here, as described above, the stopper portions 15 and 15 are not excessively reduced in strength due to the press-fitting of the support shaft member 21 into the inner cylindrical metal fitting 11, so that the durability is ensured. Vibration due to vibration input can be reliably suppressed over a long period of time.
[0017]
In the above embodiment, the stopper portion 15 is an annular shape that is disposed over the entire circumference of the inner cylindrical metal member 11, and the curly portion 19 of the rubber elastic body 18 also corresponds to the stopper portion 15 over the entire circumferential direction. By being arranged in an annular shape, the vibration isolator can exhibit an equivalent vibration isolating characteristic at any portion in the circumferential direction. Therefore, since there is no directionality of attachment of the vibration isolator to the support shaft member 21, the work for attaching the vibration isolator is simplified. However, the stopper portion can be protruded in a specific direction, and a currant portion can be provided only in the rubber elastic body portion corresponding to the protruding direction, and the vibration damping direction can be defined in a certain direction.
[0018]
Moreover, in the said embodiment, although the case where a stopper part was resin was demonstrated, a stopper part can be made from metal as needed, and can also be fixed to a large diameter part by press fit. Also by this, the large-diameter portion 12 of the inner cylinder fitting 11 provided with the stopper is hardly affected by press-fitting the support shaft member 21 into the inner cylinder fitting 11. Therefore, when the support shaft member 21 is press-fitted into the inner cylinder fitting 11, the inner cylinder fitting is not plastically deformed at the portion where the stopper portion is provided, and the extraction force of the support shaft member 21 is approximately equal to the pressure input. The function of stably supporting the inner cylindrical fitting of the support shaft member 21 can be ensured. Further, in this case, the weight of the stopper portion is heavier than that made of resin, but the strength is increased compared to that made of resin.
[0019]
In addition, in the said embodiment, although shown about the case where a vibration isolator is used as a differential mount, it is applicable similarly not only to this but another similar use. Further, since the vibration isolator is used as a differential mount, a support shaft member for cantilever support is used. However, the support shaft member may have a structure supported at both ends. In addition, the vibration isolator shown in each of the above embodiments is an example, and can be implemented in various forms without departing from the gist of the present invention.
[0020]
【The invention's effect】
According to the present invention, when the support shaft member is press-fitted into the shaft hole of the inner cylinder fitting, the large-diameter portions on both ends are not affected by the press-fitting. In the case where the stopper portion is made of metal, the large-diameter portion of the inner cylinder fitting is not plastically deformed. In addition, since the intermediate portion sandwiched between the large-diameter portions is elastically deformed by the press-fitting of the support shaft member, and the support shaft member receives an elastic reaction force from the intermediate portion, it is possible to perform pressure input without reducing the pulling force of the support shaft member. It is secured to the same extent.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view in the axial direction of a vibration isolator according to an embodiment of the present invention.
2 is a cross-sectional view of the vibration isolator taken along the line II-II shown in FIG.
FIG. 3 is a cross-sectional view showing a state where a support shaft member is press-fitted into the vibration isolator.
FIG. 4 is a cross-sectional view in the axial direction showing a vibration isolator as a comparative example.
FIG. 5 is an axial sectional view showing a conventional vibration isolator.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Inner cylinder metal fitting, 12 ... Large diameter part, 13 ... Middle part, 15 ... Stopper part, 16 ... Outer cylinder metal fitting, 18 ... Rubber elastic part, 19 ... Straight part, 21 ... Support shaft member, 22 ... Insertion part , 24 ... support part.

Claims (1)

Both end portions in the axial direction of the metal pipe bulge coaxially with respect to the intermediate portion therebetween, and the inner diameter and outer diameter thereof are larger than the inner diameter and outer diameter of the intermediate portion. The inner tube bracket,
A pair of stopper portions that are fixed to the outer peripheral surface of each large-diameter portion and project in the radial direction;
An outer cylinder fitting disposed radially outside the inner cylinder fitting including the pair of stopper portions;
A rubber elastic body that is interposed between the inner cylinder fitting and the outer cylinder fitting and elastically connects between the inner cylinder fitting and the outer cylinder fitting, and is press-fitted and fixed in the shaft hole of the inner cylinder fitting. The support shaft member elastically expands only the intermediate portion of the inner cylinder fitting, and the large diameter portion of the inner cylinder fitting is supported so as not to be affected by press fitting. Anti-vibration device.

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